The present invention relates to a fixturing apparatus and, more particularly, to a modular fixturing apparatus used to support an object undergoing manufacturing, inspection, or testing processes or the like. The invention is particularly suitable for supporting or holding a part or component undergoing quality control inspection by a coordinate measuring machine (CMM) and may also be used to support or hold objects undergoing light to moderate manufacturing processing, such as assembling, soldering, laser-jet and water-jet cutting, welding, light-machining, or the like.
A typical modular fixturing apparatus includes a platform or base plate and a series of fixturing components that can be mounted to the base plate to provide support and leveling for the part undergoing inspection. The base plate includes a plurality of mounting openings that permit the fixturing components to be secured to the base plate in a variety of different locations to hold a variety differently sized and shaped parts. These fixturing components include, for example, risers, spacers, clamps, including vacuum-based clamps, springs, fasteners, magnets, and the like which may be arranged on and secured to the base plate in a number of different configurations in order to allow a particular object to be supported and, in some cases, secured to the base plate. Furthermore, these fixturing components can be disassembled and reassembled so that the fixturing components can be reused in different configurations on the same or another base plate to create different fixture configurations to accommodate a variety of parts, ranging from, for example, a computer part to an airplane part.
Many parts have locator holes that are used as datums from which measurements are to be taken. Since the holes have their own tolerances, fixturing apparatuses use the center of the hole as the actual datum rather than the edge of hole. Furthermore, these holes vary in size with each type of part. In order to locate the center of these holes and accommodate these variations in hole sizes, universal hole locators have incorporated sliding pins with tapered ends to provide adjustable locating surfaces. However, these universal hole locators have provided limited support to the part undergoing inspection. Therefore, the number of components to set-up the part for inspection or the like increases with each locator hole. When setting up a fixturing apparatus, an increase in the number of components to hold and set up the part increases the set-up time and hence the cost of the process. Moreover, the weight of the fixturing apparatus increases.
Consequently, there is a need to provide an improved locator system that will locate the center of the datum holes while providing a holding function along at least one axis to minimize the number of fixturing components needed to set up the fixturing apparatus.